JPH05320627A - Cold-reserving material and its production - Google Patents

Abstract

PURPOSE:To obtain a cold-reserving material which is soft even when refrigerated and retains the softness even after being repeatedly used by using, as the material, a gel contg. a water-insol. water-absorbing polymer, a water-sol. polymer, water, and a hydrophilic alcohol. CONSTITUTION:A gel contg. a water-insol. water-absorbing polymer pref. having an absorption capability of pure water of 10-1,000l/g (e.g. a hydrolyzate of a starch-acrylonitrile copolymer), a water-sol. polymer (e.g. polyacrylamide), water, and a hydrophilic alcohol (e.g. glycerol is put into a container such as a bag and used as a cold-reserving material. The material, usually used as refrigerated at -30 to -5 deg.C, is soft even when refrigerated, hence can be used in the shape conforming to that of an object being cooled and in close contact with the object, and is suitable for a cooling pillow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold insulating material having a low temperature flexibility and a large cold insulating capacity.

[0002]

2. Description of the Related Art As a conventional cold insulating material having low-temperature flexibility, a water-absorbing crosslinked polymer dispersed in a continuous phase composed of a teleblock copolymer elastomer and an oil component (for example, JP-A-60-79061). Gazette); containing a vinyl chloride resin gelled by mixing a plasticizer and a hydrogel or a water-soluble polymer (for example, JP-A-63)
No. 178156) is known.

[0003]

However, these cold insulating materials have problems that the cold insulating time is insufficient and that the low temperature flexibility decreases as the number of repeated uses increases.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to obtain a cold insulating material having a longer cold storage time, excellent low temperature flexibility, and lowering low temperature flexibility even after repeated use. Reached

That is, the present invention provides a cold insulating material comprising a water-insoluble water-absorbing polymer, a water-soluble polymer, a gelled product containing water and hydrophilic alcohols; and a water-insoluble water-absorbing polymer and a water-soluble polymer. The method for producing the cold-insulating material is characterized in that water and, if necessary, hydrophilic alcohols are added to a gelled mixture of hydrophilic alcohols and the mixture is gelled again.

Examples of the water-insoluble water-absorbing polymer used in the present invention include natural water-insoluble water-absorbing polymers such as agar and gelatin, and synthetic water-absorbing resins. Examples of synthetic water absorbent resins include starch or cellulose (a) and a water-soluble monomer containing a carboxyl group and / or a sulfonic acid group and / or a monomer (b) which becomes water-soluble by hydrolysis. , A cross-linking agent (c) as an essential component, and a water-absorbent resin obtained by hydrolysis if necessary.
(A) used in the production of the water absorbent resin exemplified above,
Details of (b) and (c), ratios of (a), (b) and (c), manufacturing method and specific examples of the water absorbent resin are described in JP-A-52-25886, JP-B-53-46199, and JP-B-53-46199. JP-B-53-46200 and JP-B-55-21041
It is described in Japanese Patent Publication No.

Examples of the water absorbent resin other than those exemplified above are those obtained by polymerizing (a) and (b) (hydrolyzate of starch-acrylonitrile graft polymer,
Cellulose-acrylonitrile graft polymer hydrolyzate, etc., (a) crosslinked product (carboxymethylcellulose crosslinked product, etc.), (b) and (c) copolymer (crosslinked polyacrylamide partially hydrolyzed product, Cross-linked acrylic acid-acrylamide copolymer, cross-linked sulfonated polystyrene, vinyl ester-unsaturated carboxylic acid copolymer saponified product, cross-linked polyacrylic acid salt,
Crosslinked acrylic acid-acrylic acid ester copolymer,
(Crosslinked isobutylene-maleic anhydride copolymer, and crosslinked carboxylic acid-modified polyvinyl alcohol)
In addition, the polymer (b) having self-crosslinking (such as a self-crosslinking polyacrylic acid salt) can be mentioned. Further, two or more kinds of the water absorbent resins exemplified above may be used in combination.

Among these water-absorbent resins, preferred ones are; and, among others, a partial hydrolyzate of crosslinked polyacrylamide, a crosslinked acrylic acid-acrylic ester copolymer, a crosslinked isobutylene-maleic anhydride copolymer. And a crosslinked carboxylic acid-modified polyvinyl alcohol.

The above water-absorbent resin has a water-absorbing performance for pure water of at least 50 ml / g, particularly 100 to 1000 ml / g.
g is suitable.

The weight ratio of water to the water-insoluble water-absorbing polymer in the gel is usually 100: 0.1-10, preferably 100: 0.5-8. If the water-insoluble water-absorbent polymer is less than 0.1, the cold storage heat amount is reduced, and if it exceeds 10, the flexibility during freezing is reduced.

Examples of the water-soluble polymer used in the present invention include carboxymethyl cellulose, methyl cellulose, polyvinyl alcohol, sodium alginate, starch, pullulan and acrylamide copolymers. The acrylamide copolymer may be nonionic, anionic or cationic, and examples of the nonionic include polyacrylamide and polymethacrylamide. As anionic,
Partial hydrolyzate of polyacrylamide or polymethacrylamide, copolymer of acrylic acid or methacrylic acid with acrylamide or methacrylamide and salts thereof, acrylic acid or methacrylic acid with acrylamide or methacrylamide and 2-acrylamido-2 methylpropane sulfone Examples thereof include terpolymers with acid, vinyl sulfonic acid or vinyl methyl sulfonic acid, and salts thereof. Examples of the cationic property include a copolymer of acrylamide and acryloyl or methacryloyloxyethyltrimethylammonium chloride, a copolymer of acrylamide and trimethylammonium chloride, and the like.

Of these water-soluble polymers, preferred are nonionic and anionic acrylamide copolymers, and particularly preferred are anionic acrylamide copolymers. The water-soluble polymers exemplified above may be used in combination of two or more.

The water-soluble polymer used in the present invention is 3
It is preferable that the intrinsic viscosity measured in an aqueous 1N sodium nitrate solution at 0 ° C. is 10 (dl / g) or more, and the spinnability of the 0.1% by weight aqueous solution is 50 mm or more. By using a material having a high spinnability, the shape retention of the cold insulating material becomes good.

The weight ratio of water to the water-soluble polymer in the gel is generally 100: 0.1-10, preferably 10
It is 0: 0.5-8. If the water-soluble polymer is less than 0.1, the shape retention at room temperature will be reduced, and if it exceeds 10, the flexibility at freezing will be reduced.

The weight ratio of the water-insoluble water-absorbing polymer to the water-soluble polymer in the cold insulating material of the present invention is usually 1: 0.1-10.
And preferably 1: 0.2 to 3. If the water-soluble polymer is less than 0.1, the number of times of repeated use decreases, and 10
When it exceeds the above range, it takes time and effort to take out the highly spinnable gel-like material from the manufacturing equipment during the production of the gel-like material.

In the hydrophilic alcohols used in the present invention, hydrophilic means water-soluble and water-dispersible, and examples thereof include glycerin, ethylene glycol, diethylene glycol, ethanol, and hydrophilic polyethers [polyethylene. Glycol, poly (oxyethylene
[Oxypropylene) triol, poly (oxyethylene / oxypropylene) glycol, poly (oxyethylene / oxypropylene) glycol / monoalkyl ether and the like]. The hydrophilic alcohols exemplified above may be used in combination of two or more kinds. Of these, preferred are hydrophilic polyethers, diethylene glycol, glycerin and their combinations, and particularly preferred are glycerin and glycerin in combination with hydrophilic polyethers and / or diethylene glycol.

The weight ratio of water to hydrophilic alcohol in the cold insulating material of the present invention is usually 100: 1 to 80, preferably 10.
It is 0:10 to 65. If the hydrophilic alcohols are less than 1, the flexibility at the time of freezing decreases, and if it exceeds 80, the cold storage time decreases.

The weight ratio of the water-soluble polymer to the hydrophilic alcohol in the gel material of the present invention is usually 1:10 to 60,
It is preferably 1: 20-40. Particularly preferably 1:
25-35. If it is less than 10, the flexibility during freezing is reduced, and if it exceeds 60, the number of times of repeated use is reduced.

The cold insulating material of the present invention may be mixed with a filler or a glass powder within a range that does not cause a problem depending on the purpose of use. Examples of the filler include calcium carbonate, aluminum oxide, aluminum octylate, powdered mica, expanded polyethylene, expanded polystyrene, expanded urethane, talc, cork and the like. Examples of the glass powder include borate glass, silicate glass, phosphate glass and oxide glass. Oxide glass is used by crushing plate glass after melting and cooling. The particle size of the glass powder is not particularly limited, but it is desirable that the particle size be small and have the same particle size.

If desired, the cold insulating material of the present invention may be mixed with other additives such as colorants such as pigments, heat-sensitive dyes, preservatives, ultraviolet absorbers and antioxidants.

The gel-like cold insulating material of the present invention is usually in a form in which a gel-like material is filled in a packaging member. The shape of the packaging member may be any shape such as a bag shape, a box shape, a cylindrical shape, a ball shape, and a spherical shape, and is not particularly limited. The size can also be arbitrarily set within a range capable of exerting a cold storage capacity according to the purpose of use.

The material of the packaging member is not particularly limited as long as it is water resistant. For example, polyethylene / nylon type laminated film, polyethylene / nylon / EVA laminated film, etc., even if thin, have film strength, water resistance and heat sealability. It is convenient to use a bag with excellent workability as a bag.

As an example of the method for producing the cold insulating material of the present invention, the water-insoluble water-absorbing polymer and the water-soluble polymer are mixed in a powder state by a universal mixer or the like. 1 or 2 in this powder mixture
Hydrophilic alcohols of one kind or more are added and sufficiently stirred at 50 to 60 ° C to form a gel. Next, after adding water, optionally one or more alcohols and, if necessary, a filler, glass powder or other additives to the gel-like product, a universal mixer is sufficient. Mix and re-gel and fill water resistant plastic packaging material,
The heat insulating material of the present invention can be obtained by heat fusion or sealing with an adhesive or the like. When hydrophilic alcohols are used for gelation again, it is more efficient in working to use hydrophilic alcohols different from those used for the first gelation.

The gel-like cold insulating material of the present invention is usually -30 to-
5 ° C., preferably −20 to −15 ° C.,
It can be used as a cold insulating material by freezing for 1 to 24 hours.

[0025]

【Example】

The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Parts in the examples are parts by weight. Example 1 Water-absorbent resin [Sunwet IM- manufactured by Sanyo Kasei Co., Ltd.
4 parts of 5,000] and 4 parts of acrylamide copolymer [SAN FLOOK AH-210P manufactured by Sanyo Kasei Co., Ltd.] were sufficiently mixed with a universal mixer. 64 parts of glycerin was added thereto, and the mixture was stirred at 50 ° C. for 1 hour and 30 minutes. Then, the mixture was cooled to 25 ° C., 116 parts of water, 6 parts of diethylene glycol, and 6 parts of polyethylene glycol (molecular weight of 300 or less abbreviated as PEG-300) were added, and the mixture was thoroughly mixed with a universal mixer to give a white gel-like cold insulating material of the present invention. Obtained. Cooling time of the obtained cold insulating material,
Table 1 shows the results of testing the flexibility at the time of keeping cold and the flexibility (reversibility) when repeatedly frozen after 20 times of use.

Example 2 In Example 1, diethylene glycol was replaced with poly (octyethylene.oxypropylene) glycol monobutyl ether (New Pol 50HB-manufactured by Sanyo Kasei Co., Ltd.).
660) and a white gel-like cold insulating material of the present invention was obtained by the same method. The performance measurement results of this product are shown in Table 1.

Example 3 In Example 1, water, diethylene glycol, PEG
A white gel-like cold insulating material of the present invention was obtained in exactly the same manner except that 20 parts of talc powder was added when -300 was added. The performance measurement results of this product are shown in Table 1.

Example 4 A white gel-like cold insulating material of the present invention was obtained in the same manner as in Example 1 except that 5 parts of starch was used instead of 4 parts of Sanfloc AH-210P. The performance measurement results of this product are shown in Table 1.

Example 5 In Example 4, water, diethylene glycol, PEG
A white gel-like cold insulating material of the present invention was obtained in the same manner except that 0.5 part of borate glass powder was added when -300 was added. The performance measurement results of this product are shown in Table 1.

Comparative Example 1 Sunwet IM-5000 3 parts, Sunfloc AH
-210P 3 parts were thoroughly mixed with a universal mixer. 120 parts of water and glycerin 6 prepared separately from this powder mixture
8 parts, 3 parts of ethylene glycol, and 3 parts of PEG-300 were added to an aqueous solution, and the mixture was stirred for about 5 minutes and stood still to obtain a white gel-like comparative cold insulator. The performance measurement results of this product are shown in Table 1.

Comparative Example 2 A comparative cold insulating material was prepared based on the example of JP-A-60-79061. The performance measurement results of this product are shown in Table 1.

Comparative Example 3 A comparative cold insulating material was prepared based on Example 1 of JP-A-63-178156. The performance measurement results of this product are shown in Table 1.

[0034]

[Table 1]

Note 1: The cold storage time was such that a product that had been frozen at -20 ° C for 12 hours was left in a room at 25 ° C, and the time until it reached 10 ° C was measured. Sample weight is 600g, 250mm ×
A 250 mm x 10 mm polyethylene / nylon-based laminate bag was used.

Note 2 The initial flexibility was confirmed by pressing a finger at -20 ° C. for 12 hours and pressing it with a finger. ◯ indicates that it is easily deformed, Δ indicates that it is deformed when it is strongly pressed, and × indicates that it is not deformed.

Note 3 The softness-holding property is determined by immersing a sample frozen at -20 ° C for 12 hours in warm water at 25 ° C and returning it to room temperature.
After repeating 0 times, the product was further frozen at −20 ° C. for 12 hours, and the state when pressed with a finger was confirmed. The criterion is the same as in (2).

[0038]

【The invention's effect】

The present invention has the following effects. (1) The cold storage time is improved as compared with the conventional one. (2) The cold insulating material of the present invention is usually used after being frozen at -30 to -5 ° C. However, it has flexibility even during freezing, and this flexibility does not change even after repeated use. The conventional cold insulating material loses flexibility during freezing during repeated use, and finally solidifies. (3) It can be used by closely adhering to the shape of the object to be kept cold, and it is the same when repeatedly used. Because of the above effects, the cold insulating material obtained according to the present invention is useful for cold insulating pillows and cold insulating of blood, specimens, frozen desserts, foods and the like. Further, it is useful as a cold insulation material used for preventing a failure at the time of cooling down after exercising a race or after a race, for treating a leg and a hoof of a horse, and for cooling down after a human exercise.

Claims (7)

[Claims] 1. A cold insulating material comprising a gel-like material containing a water-insoluble water-absorbing polymer, a water-soluble polymer, water and hydrophilic alcohols. 2. The cold insulating material according to claim 1, wherein the water-insoluble water-absorbing polymer has a water-absorbing performance for pure water of 100 to 1000 ml / g. 3. The water-soluble polymer is acrylamide, (meth) acrylic acid (salt), 2-methyl-2-acrylamidopropanesulfonic acid (salt), (meth) acryloyloxyethyltrimethylammonium quaternary salt, (meth). At least one of acryloyloxyethyl dialkylamine salts
The cold insulating material according to claim 1 or 2, which is a (co) polymer having at least one species as a constituent unit. 4. The water-soluble polymer has an intrinsic viscosity of 10 (dl / dl) measured at 30 ° C. in a 1N sodium nitrate aqueous solution.
g) or more and the spinnability of a 0.1% by weight aqueous solution is 5
The cold insulating material according to any one of claims 1 to 3, which has a length of 0 mm or more. 5. The cold insulating material according to claim 1, wherein the hydrophilic alcohol is one or more selected from ethanol, glycerin, diethylene glycol, ethylene glycol or hydrophilic polyethers. 6. The cold insulating material according to claim 1, wherein a packaging member is filled with the gel-like material. 7. A mixture of a water-insoluble water-absorbing polymer, a water-soluble polymer and hydrophilic alcohols, which is gelled,
The method for producing a cold insulating material according to any one of claims 1 to 5, wherein water and hydrophilic alcohols are added as necessary and gelation is carried out again.